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首页> 外文期刊>European Journal of Soil Science >Multifractal properties of porosity as calculated from computed tomography (CT) images of a sandy soil, in relation to soil gas diffusion and linked soil physical properties.
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Multifractal properties of porosity as calculated from computed tomography (CT) images of a sandy soil, in relation to soil gas diffusion and linked soil physical properties.

机译：由砂土的计算机断层扫描（CT）图像计算得出的孔隙度的多重分形特性，涉及土壤气体扩散和相关土壤物理特性。

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Relationships between soil porosity and diffusive gas flux are poorly understood, partly because of a difference in measurement scales between the two. The complexity of soil pore systems can be described by multifractal analysis at the microscopic scale, whereas relative soil gas diffusion coefficients ( Ds/ Do) are usually evaluated at the core scale. The objectives of this study were to (i) define a quantitative 'pseudo-macroporosity gas' from high-resolution X-ray computed tomography (CT) scanning images and characterize it for 10 intact soil cores, (ii) analyse the frequency distribution of pseudo-macropores gas in the columns with a multifractal approach and (iii) assess relationships between Ds/ Do measured at the core scale and multifractal parameters describing the pore system heterogeneity within a core. The shape and symmetry of the singularity spectra and the degree of curvilinearity of the Renyi spectra show that the multifractal behaviour of the pseudo-macroporosity gas distribution for a given CT image thresholding varied among soil columns. Correlations found between Ds/ Do and some parameter estimates of the singularity spectrum suggest that the distribution of pseudo-macropores gas, depending on the CT image thresholding, influenced Ds/ Do. In particular, a strong correlation between Ds/ Do and the entropy dimension (D q=1 ) indicates that Ds/ Do was influenced by the degree of spatial heterogeneity of the pseudo-macroporosity gas distribution. The correlation dimension (D q=2 ) was also linked to Ds/ Do, suggesting that a second-order power law might describe the scaling relationship between pseudo-macroporosity gas distribution and Ds/ Do. In conclusion, the multifractal description of soil porosity as calculated from CT images may be regarded as a way to improve our understanding of gas movement in soils at the core scale.
机译：人们对土壤孔隙度与扩散气体通量之间的关系了解甚少，部分原因是两者之间的测量尺度不同。土壤孔隙系统的复杂性可以通过微观尺度上的多重分形分析来描述，而相对的土壤气体扩散系数（Ds / Do）通常是在核心尺度上评估的。这项研究的目的是（i）从高分辨率X射线计算机断层扫描（CT）扫描图像中定义定量的“假巨微气体”，并对其10个完整的土壤岩心进行表征，（ii）分析频率分布。用多重分形方法分析柱中的假大孔气体，（iii）评估岩心尺度上测得的Ds / Do与描述岩心内孔隙系统非均质性的多重分形参数之间的关系。奇异谱的形状和对称性以及人意谱的曲线度表明，对于给定的CT图像阈值，假巨巨相气体分布的多重分形行为在土柱之间变化。在Ds / Do与奇异谱的一些参数估计值之间发现的相关性表明，根据CT图像阈值，伪大孔气体的分布会影响Ds / Do。尤其是，Ds / Do与熵维（D q = 1）之间的相关性强，表明Ds / Do受拟宏观尺度气体分布的空间异质性程度影响。相关维数（D q = 2）也与Ds / Do相关联，表明二阶幂定律可能描述了拟巨巨气体分布与Ds / Do之间的比例关系。总之，由CT图像计算出的土壤孔隙度的多重分形描述可能被视为一种方法，可以提高我们对核心尺度下土壤中气体运动的理解。

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